Other underwater viewing devices include such things as diving masks, air mattresses with windows, and glass bottom boats. None of these devices are intended to enhance images, for example by magnifying or giving wide-angle views. Another disadvantage is that these devices either require the user and/or the masks to be submerged in the water or are large and unwieldy. Often these devices can only be used by one person at a time.
U.S. Pat. No. 4,145,783 (Rhodes) describes a window within a floation housing where the housing is used for the collection and storage of items and the window lies beneath the surface of the water. Having the window below the surface of the water cuts down on visibility from the sides of the device, and forces the viewer to position him/herself directly over the window. This means the viewer must be standing in the water. Another disadvantage to having the window below the surface of the water is that water can be splashed and will collect in pools on the surface of the window which will cut down on the viewing area. Another disadvantage of this configuration is that the window is always and only parallel to the surface of the water.
U.S. Pat. No. 3,808,621 (French) describes a swimmer's viewing float. This patent mentions a lensing action stemming from the convexity of the float's bottom surface. It is the hollow air filled space between the two surfaces of the float that French claims creates the lens and not the water that the float is in. Again, water is not brought in any way into the device. Also the user is completely in the water while using the swimmer's float.
All art referenced above, including both patents and underwater viewing devices on the market, are designed to keep water out of an apparatus. The present invention requires that water be brought into a cavity to activate the image enhancement (lensing action). Also most devices require the viewer to be in the water with the device, and most of these devices are more than two parts. The present invention can be used with the viewer either in or out of the water, and is at most only two parts.